Drug-resistant Temporal Lobe Epilepsy Research Articles

Surgical outcomes in patients with drug-resistant bilateral temporal lobe epilepsy confirmed via magnetic resonance imaging

Introduction. In patients with drug-resistant temporal lobe epilepsy (TLE), surgical treatment is aimed to resect an epileptogenic zone (EZ) followed by seizure control. Despite complicated EZ location, surgical resection should be considered as a treatment of choice in bilateral TLE.
 Objective: to evaluate surgical outcomes and factors contributing to outcomes in patients with drug-resistant bilateral TLE confirmed via magnetic resonance imaging.
 Materials and methods. The study included patients with unilateral (n = 50) and bilateral (n = 50) temporal lobe involvement. The results of surgical treatment were evaluated according to the classification of J. Engel (1993).
 Results. Favorable outcomes of surgical treatment (Engel I and Engel II) in the group with unilateral temporal lobe involvement were found in 98% of patients after 12 months, in 88% after 24 months, and in 100% after 48 and 60 months after surgery. In the group with bilateral temporal lobe involvement outcomes of surgical treatment were favorable in 41% of patients after 12 months, in 50% after 24 months, in 39% after 48 months, and in 50% of patients after 60 months post-surgery.
 Conclusion. Early onset, burdened perinatal history, and MRI-confirmed left temporal lobe involvement contribute to the poor outcome (Engel III and Engel IV) in the bilateral TLE group. Engel I outcomes were more common in the patients with unilateral TLE while Engel IIIV outcomes were more common in the patients with bilateral TLE.

Cardiovascular autonomic function and baroreflex sensitivity in drug-resistant temporal lobe epilepsy

ObjectiveTemporal lobe epilepsy (TLE) is often associated with autonomic manifestations. Sudden unexpected death in epilepsy (SUDEP) is a leading cause of mortality in epilepsy. Cardiac disturbances and autonomic dysfunction are the potential mechanisms behind SUDEP. Though heart rate variability (HRV) and autonomic function tests are well studied in drug-resistant temporal lobe epilepsy, there is a paucity of data on baroreflex sensitivity (BRS), a better marker of cardiac mortality in this population. We aimed to study the interictal cardiac autonomic function and BRS in people living with drug-resistant temporal lobe epilepsy compared to healthy controls. Materials and methodsThirty drug-resistant temporal lobe epilepsy (TLE) individuals and thirty healthy volunteers were recruited. Heart rate variability at rest, heart rate and blood pressure (BP) at rest, during deep breathing, postural change, BP response to isometric handgrip exercise, and baroreflex sensitivity were recorded in all study participants. The results were analyzed and compared between the two groups. ResultsCompared to controls, the resting heart rate, HRV, parasympathetic reactivity test, and BRS significantly differed in people living with drug-resistant TLE. Time-domain indices including SDNN (p < 0.001), RMSSD (p < 0.001), NN50 (p < 0.001), and pNN50 (p < 0.001) were significantly reduced in the patients compared to controls. In frequency-domain indices, the total power was reduced (p < 0.001) in drug-resistant TLE. The parasympathetic reactivity such as changes in heart rate during deep breathing (E: I) (p < 0.02) and postural change (30:15) (p < 0.005) were significantly reduced in the patients. Baroreflex sensitivity was also significantly reduced in the drug-resistant TLE group (p < 0.001). ConclusionThe present study findings are suggestive of parasympathetic dysfunction in drug-resistant TLE. Reduced HRV and BRS may increase the risk of SUDEP in people living with epilepsy.

Stereoelectroencephalography-based research on the value of drug-resistant temporal lobe epilepsy auras: A retrospective single-center study

PurposeTo explore the localization value of drug-resistant temporal lobe epilepsy (TLE) aura for preoperative evaluation, based on stereoelectroencephalography (SEEG), and its prognostic value on the surgical outcome. MethodsThe data of patients with drug-resistant TLE who had SEEG electrodes implanted during preoperative evaluation at the First Affiliated Hospital of the University of Science and Technology of China (Hefei, China) were retrospectively analyzed. The patients were divided into aura-positive and aura-negative groups according to the presence of aura in seizures. To explore the clinical features of aura, we evaluated the localizing and prognostic values of aura for the outcome of anterior temporal lobectomy based on SEEG. ResultsAmong forty patients, twenty-seven patients were in the aura-positive group and ten (25.0%) patients had multiple auras. The most common TLE aura was abdominal aura [thirteen (34.2%) patients]. The postoperative seizure frequency was significantly reduced in the preoperative aura-positive patients compared to the preoperative aura-negative patients (P = 0.011). Patients with abdominal (P = 0.029) and single (P = 0.036) auras had better surgical prognoses than aura-negative patients. In the preoperative evaluation, aura-positive patients had a better surgical outcome if the laterality of positron emission tomography-computed tomography (PET-CT) hypometabolism was concordant with the epileptogenic focus identified with SEEG (P = 0.031). A good postoperative epileptic outcome in aura-positive patients was observed among those with hippocampal sclerotic medial temporal lobe epilepsy (P = 0.025). ConclusionEpileptic aura is valuable for the localization of the epileptogenic focus. Abdominal aura and single aura were good predictors of better surgical outcomes. Among patients with a preoperative diagnosis of hippocampal sclerosis or with laterality of PET-CT hypometabolism concordant with the epileptogenic focus identified using SEEG, those with aura are likely to benefit from surgery.

Sclérose hippocampique associée à l’épilepsie : conséquences cliniques, histopathologie et évolution avec l’âge

Hippocampal sclerosis is the most frequent etiology of patients with drug-resistant mesial temporal lobe epilepsy, which is the most frequent localization for focal epilepsy. Hippocampal sclerosis is the consequence of a cerebral aggression during early childhood, called the initial precipitating event, the most frequent of which are: febrile seizure, intracranial infection, hypoxia, or cranial trauma. The epilepsy onset usually occurs a few years after this event, with an association of focal temporal seizures and rarer secondarily generalized tonic-clonic seizures. Most patients have a drug-resistant focal epilepsy, with a failure of two different and adequate antiepileptic drugs to achieve seizure freedom. Patients also demonstrated with cognitive impairment, with a typical episodic memory impairment affecting both verbal and non-verbal episodic memory. Cognitive impairment is however more diffuse than the sole episodic memory impairment, and also affects language, visuo-spatial processing, and executive functions. With aging, subjects demonstrated a progressive cognitive decline, that appears to parallel the decline associated with normal aging, but starts earlier and from a lower global cognitive functioning with less cognitive reserve. Patients may therefore reach an impairment threshold sooner than healthy subjects, and are much more vulnerable to any other disease that impairs cognitive functioning. Patients exhibited cortical and subcortical atrophy patterns on volumetric brain MRI similar to normal aging in its distribution, but with an earlier pattern of atrophy (4.5 years sooner in patients than in healthy subjects). Hippocampal sclerosis is associated with amyloid and tau deposits inside the hippocampus, which increases with the subjects’ age. Those deposits pattern is close to the one observed in patients with tau / amyloïd neurodegenerative diseases, which demonstrates a bilateral relationship between epilepsy, hippocampal sclerosis, and neurodegenerative diseases. Clinical consequences of such a relationship are yet to be precisely determined.

The relationship between memory and quality of life is mediated by trait anxiety in patients with temporal lobe epilepsy.

Memory deficits are very frequent in patients with drug-resistant epilepsy, but they predict a small proportion of variance of their quality of life (QOL) in previous studies, possibly due to the lack of consideration of mediating factors of this relationship. This study aimed to examine whether trait anxiety mediates the relationship between memory and QOL in this population, controlling the influence of demographic and seizure-related factors. In this cross-sectional study, 119 adults with drug-resistant temporal lobe epilepsy (TLE) underwent a neuropsychological evaluation, in which memory, anxiety, and QOL were assessed. In the total sample, better delayed memory had an effect on better QOL indirectly through lower trait anxiety (B = 0.13, SE = 0.06, p = 0.04, abcs = 0.13; κ2 = 0.18; PMind = 0.76). Additionally, delayed memory has not a direct association with QOL (B = 0.04, SE = 0.09, p = 0.64, Cohen's f2 = 0.005; PMdir = 0.24), and the total effect of delayed memory on QOL tended to reach statistical significance (B = 0.17, SE = 0.10, p = 0.08). The proposed mediation model yielded excellent fit (CFI = 1.00, RMSEA = 0.0001, SRMR = 0.009, and χ2 (1) = 0.50, p = 0.48) and explained 38% of the variance of QOL. These findings suggest that trait anxiety is an important factor in understanding the relationship between memory and QOL in patients with TLE, considering the influence of demographic and seizure-related variables, and may have relevant implications for decision-making in this population.

Volume of hippocampal activation as a determining factor for the lateralisation of the epileptogenic zone in patients with drug-resistant mesial temporal lobe epilepsy

IntroductionApproximately 30% of patients with mesial temporal lobe epilepsy (MTLE) will develop drug resistance, which requires early surgical treatment. The success of the surgical procedure largely depends on the correct lateralisation of the epileptogenic zone, which can only be determined in 70% of patients with such conventional diagnostic tools as video electroencephalography and volumetric structural magnetic resonance imaging. We evaluated the performance of a memory functional magnetic resonance imaging (fMRI) paradigm in lateralising the epileptogenic zone in patients with drug-resistant MTLE. MethodsWe included 18 patients with MTLE attended at the Instituto Neurológico Colombiano in Medellin (Colombia) between 2018 and 2019. The volume of functional activation in both temporal lobes was determined with a memory fMRI paradigm. A concordance analysis was performed to compare the performance of fMRI against that of conventional tests. ResultsIn patients with left MTLE, lower total activation was found in the hemisphere ipsilateral to the epileptogenic zone as compared to the contralateral hemisphere (121.15 ± 16.48 voxels vs 170.23 ± 17.8 voxels [P < .001]), showing substantial concordance with conventional tests. Patients with right MTLE displayed lower hippocampal activation ipsilateral to the epileptogenic zone (18.5 ± 3.38 voxels vs 27.8 ± 3.77 voxels in the contralateral hippocampus [P = .048]), showing moderate concordance with conventional tests. ConclusionsThese findings suggest that lower functional activation as determined by a memory fMRI paradigm has a high level of concordance with conventional tests for lateralising the epileptogenic zone in patients with drug-resistant MTLE.

Optimizing deep brain stimulation for the treatment of drug-resistant temporal lobe epilepsy: a pilot study.

The authors sought to determine the antiseizure effects of deep brain stimulation (DBS) of the parahippocampal cortex (PHC) for treatment of drug-resistant mesial temporal lobe epilepsy (MTLE). After a 3-month baseline period, 6 adult patients with drug-resistant MTLE and hippocampal sclerosis (HS) had stereoelectroencephalography (SEEG)-DBS electrodes implanted at the PHC for identification of the seizure onset zone (SOZ). Patients entered an 8-month, randomized, double-blind protocol for DBS, followed by a 12-month open-phase study. Monthly reports of seizure frequency were collected, with separate counting of focal seizures with or without awareness impairment (focal impaired awareness seizures [FIAS] or focal aware seizures [FAS], respectively) and focal evolving to bilateral generalized tonic clonic seizures (GTCS). Stimulation parameters were 130 Hz, 450 μsec, 2.5-3 V, and cyclic stimulation 1 minute on/4 minutes off. The total seizure rate decrement during follow-up was 41% (CI 25%-56%), with better seizure control for GTCS (IQR 19%-20%) and FIAS (IQR 0%-16%), with FAS being less responsive (IQR 67%-236%). No neuropsychological deterioration was observed. PHC DBS induced important antiseizure effects in patients with incapacitating FIAS and GTCS, most likely through blocking the propagation of hippocampal-onset seizures. The PHC target can be easily and safely approached due to positioning away from vascular structures, and there was no evidence of DBS-induced cognitive deterioration.

Localizing seizure onset zones in surgical epilepsy with neurostimulation deep learning.

In drug-resistant temporal lobe epilepsy, automated tools for seizure onset zone (SOZ) localization that use brief interictal recordings could supplement presurgical evaluations and improve care. Thus, the authors sought to localize SOZs by training a multichannel convolutional neural network on stereoelectroencephalography (SEEG) cortico-cortical evoked potentials. The authors performed single-pulse electrical stimulation in 10 drug-resistant temporal lobe epilepsy patients implanted with SEEG. Using 500,000 unique poststimulation SEEG epochs, the authors trained a multichannel 1-dimensional convolutional neural network to determine whether an SOZ had been stimulated. SOZs were classified with mean sensitivity of 78.1% and specificity of 74.6% according to leave-one-patient-out testing. To achieve maximum accuracy, the model required a 0- to 350-msec poststimulation time period. Post hoc analysis revealed that the model accurately classified unilateral versus bilateral mesial temporal lobe seizure onset, as well as neocortical SOZs. This was the first demonstration, to the authors' knowledge, that a deep learning framework can be used to accurately classify SOZs with single-pulse electrical stimulation-evoked responses. These findings suggest that accurate classification of SOZs relies on a complex temporal evolution of evoked responses within 350 msec of stimulation. Validation in a larger data set could provide a practical clinical tool for the presurgical evaluation of drug-resistant epilepsy.

Temporal-insular spreading time in temporal lobe epilepsy as a predictor of seizure outcome after temporal lobectomy.

Insular involvement in temporal lobe epilepsy (TLE) has gradually been recognized since the widespread use of stereoelectroencephalography (SEEG). However, the correlation between insular involvement and failed temporal lobe surgery remains unclear. In this study, we analyzed the surgical outcomes of TLE patients who underwent temporal and insular SEEG recordings and explored the predictors of failed anterior temporal lobectomy (ATL) in these patients with temporal seizures.Forty-one patients who underwent ATL for drug-resistant TLE were examined using temporal and insular SEEG recordings. The clinical characteristics, SEEG data, and postoperative seizure outcomes of these patients were analyzed, and multivariate analysis was used to identify the predictors of surgical outcome.In this series, the ictal temporal discharges invaded the insula in 39 (95.1%) patients. Twenty-three (56.1%) patients were seizure-free (Engel class I) after ATL with at least 1 year follow-up. Only temporal-insular spreading time (TIST) was an independent predictor of postoperative seizure-free outcomes (P = .035). By creating receiver operating characteristic curves for TIST, 400 milliseconds was identified as the cutoff for classification. All patients were classified into 2 groups (TIST ≤ 400 milliseconds and TIST > 400 milliseconds) based on the cutoff value; the difference in seizure-free rates between the 2 groups was significant (P = .001).The very early insular involvement in TLE may be associated with poorer seizure outcomes after ATL. Our findings may be helpful for estimating the appropriate operative procedures and will be valuable for evaluating the prognosis of TLE patients with temporal-insular SEEG recordings and temporal lobectomy.

'Hippocampal innate inflammatory gliosis only' in pharmacoresistant temporal lobe epilepsy.

Drug-resistant mesial-temporal lobe epilepsy is a devastating disease with seizure onset in the hippocampal formation. A fraction of hippocampi samples from epilepsy-surgical procedures reveals a peculiar histological pattern referred to as 'gliosis only' with unresolved pathogenesis and enigmatic sequelae. Here, we hypothesize that 'gliosis only' represents a particular syndrome defined by distinct clinical and molecular characteristics. We curated an in-depth multiparameter integration of systematic clinical, neuropsychological as well as neuropathological analysis from a consecutive cohort of 627 patients, who underwent hippocampectomy for drug-resistant temporal lobe epilepsy. All patients underwent either classic anterior temporal lobectomy or selective amygdalohippocampectomy. On the basis of their neuropathological exam, patients with hippocampus sclerosis and 'gliosis only' were characterized and compared within the whole cohort and within a subset of matched pairs. Integrated transcriptional analysis was performed to address molecular differences between both groups. 'Gliosis only' revealed demographics, clinical and neuropsychological outcome fundamentally different from hippocampus sclerosis. 'Gliosis only' patients had a significantly later seizure onset (16.3 versus 12.2 years, P = 0.005) and worse neuropsychological outcome after surgery compared to patients with hippocampus sclerosis. Epilepsy was less amendable by surgery in 'gliosis only' patients, resulting in a significantly worse rate of seizure freedom after surgery in this subgroup (43% versus 68%, P = 0.0001, odds ratio = 2.8, confidence interval 1.7-4.7). This finding remained significant after multivariate and matched-pairs analysis. The 'gliosis only' group demonstrated pronounced astrogliosis and lack of significant neuronal degeneration in contrast to characteristic segmental neuron loss and fibrillary astrogliosis in hippocampus sclerosis. RNA-sequencing of gliosis only patients deciphered a distinct transcriptional programme that resembles an innate inflammatory response of reactive astrocytes. Our data indicate a new temporal lobe epilepsy syndrome for which we suggest the term 'Innate inflammatory gliosis only'. 'Innate inflammatory gliosis only' is characterized by a diffuse gliosis pattern lacking restricted hippocampal focality and is poorly controllable by surgery. Thus, 'innate inflammatory gliosis only' patients need to be clearly identified by presurgical examination paradigms of pharmacoresistant temporal lobe epilepsy patients; surgical treatment of this subgroup should be considered with great precaution. 'Innate inflammatory gliosis only' requires innovative pharmacotreatment strategies.

Reorganization of the Brain Extracellular Matrix in Hippocampal Sclerosis

The extracellular matrix (ECM) is an important regulator of excitability and synaptic plasticity, especially in its highly condensed form, the perineuronal nets (PNN). In patients with drug-resistant mesial temporal lobe epilepsy (MTLE), hippocampal sclerosis type 1 (HS1) is the most common histopathological finding. This study aimed to evaluate the ECM profile of HS1 in surgically treated drug-resistant patients with MTLE in correlation to clinical findings. Hippocampal sections were immunohistochemically stained for aggrecan, neurocan, versican, chondroitin-sulfate (CS56), fibronectin, Wisteria floribunda agglutinin (WFA), a nuclear neuronal marker (NeuN), parvalbumin (PV), and glial-fibrillary-acidic-protein (GFAP). In HS1, besides the reduced number of neurons and astrogliosis, we found a significantly changed expression pattern of versican, neurocan, aggrecan, WFA-specific glycosylation, and a reduced number of PNNs. Patients with a lower number of epileptic episodes had a less intense diffuse WFA staining in Cornu Ammonis (CA) fields. Our findings suggest that PNN reduction, changed ECM protein, and glycosylation expression pattern in HS1 might be involved in the pathogenesis and persistence of drug-resistant MTLE by contributing to the increase of CA pyramidal neurons’ excitability. This research corroborates the validity of ECM molecules and their modulators as a potential target for the development of new therapeutic approaches to drug-resistant epilepsy.

Reduced Metabotropic Glutamate Receptor Type 5 Availability in the Epileptogenic Hippocampus: An in vitro Study.

Abnormalities in the expression of metabotropic glutamate receptor type 5 (mGluR5) have been observed in the hippocampus of patients with drug-resistant mesial Temporal Lobe Epilepsy (mTLE). Ex-vivo studies in mTLE hippocampal surgical specimens have shown increased mGluR5 immunoreactivity, while in vivo whole brain imaging using positron emission tomography (PET) demonstrated reduced hippocampal mGluR5 availability. To further understand mGluR5 abnormalities in mTLE, we performed a saturation autoradiography study with [3H]ABP688 (a negative mGluR5 allosteric modulator). We aimed to evaluate receptor density (Bmax) and dissociation constants (KD) in hippocampal mTLE surgical specimens and in non-epilepsy hippocampi from necropsy controls. mTLE specimens showed a 43.4% reduction in receptor density compared to control hippocampi, which was independent of age, sex and KD (multiple linear regression analysis). There was no significant difference in KD between the groups, which suggests that the decreased mGluR5 availability found in vivo with PET cannot be attributed to reduced affinity between ligand and binding site. The present study supports that changes within the epileptogenic tissue include mGluR5 internalization or conformational changes that reduce [3H]ABP688 binding, as previously suggested in mTLE patients studied in vivo.

Effects of epilepsy surgery on sleep macrostructure and microstructure in patients with drug-resistant temporal lobe epilepsy due to hippocampal sclerosis: a prospective controlled polysomnographic study

Effects of epilepsy surgery on sleep macrostructure and microstructure in patients with drug-resistant temporal lobe epilepsy due to hippocampal sclerosis: a prospective controlled polysomnographic study

Anterior nucleus of the thalamus deep brain stimulation vs temporal lobe responsive neurostimulation for temporal lobe epilepsy.

Based on the promising results of randomized controlled trials, deep brain stimulation (DBS) and responsive neurostimulation (RNS) are used increasingly in the treatment of patients with drug-resistant epilepsy. Drug-resistant temporal lobe epilepsy (TLE) is an indication for either DBS of the anterior nucleus of the thalamus (ANT) or temporal lobe (TL) RNS, but there are no studies that directly compare the seizure benefits and adverse effects associated with these therapies in this patient population. We, therefore, examined all patients who underwent ANT-DBS or TL-RNS for drug-resistant TLE at our center. We performed a retrospective review of patients who were treated with either ANT-DBS or TL-RNS for drug-resistant TLE with at least 12 months of follow-up. Along with the clinical characteristics of each patient's epilepsy, seizure frequency was recorded throughout each patient's postoperative clinical course. Twenty-six patients underwent ANT-DBS implantation and 32 patients underwent TL-RNS for drug-resistant TLE. The epilepsy characteristics of both groups were similar. Patients who underwent ANT-DBS demonstrated a median seizure reduction of 58% at 12-15 months, compared to a median seizure reduction of 70% at 12-15 months in patients treated with TL-RNS (p > .05). The responder rate (percentage of patients with a 50% decrease or more in seizure frequency) was 54% for ANT-DBS and 56% for TL-RNS (p > .05). The incidence of complications and stimulation-related side effects did not significantly differ between therapies. We demonstrate in our single-center experience that patients with drug-resistant TLE benefit similarly from either ANT-DBS or TL-RNS. Selection of either ANT-DBS or TL-RNS may, therefore, depend more heavily on patient and provider preference, as each has unique capabilities and configurations. Future studies will consider subgroup analyses to determine if specific patients have greater seizure frequency reduction from one form of neuromodulation strategy over another.

Understanding the problems with recruitment in surgical randomized trials: A lesson from landmark trials on temporal lobe epilepsy

BackgroundSurgical randomized trials are difficult to accomplish. One major problem is recruitment of a sufficient number of patients to address the clinical problem. MethodsWe review the various ways patient recruitment in surgical RCTs can be promoted. We examine two landmark trials on the surgical treatment of temporal lobe epilepsy (TLE), one that was successful, and one which did not attain the target number of participants. DiscussionBoth designs of the Canadian and American trials of surgery for TLE included a benefit to participants: the Canadian trial gave a chance to have immediate access to investigation and treatment, as compared to a 1 year delay (considered ‘standard care’ in that center), while the American trial offered free surgical management to both arms. Patients were recruited and treatments randomly allocated prior to knowing for certain whether they were surgical candidates or not. This design choice may have helped circumvent the ‘equipoise problem’. The Canadian trial offered participation to drug-resistant patients that were already routinely referred to surgical centers, while the success of the American trial which limited recruitment to the early period of drug resistance was dependent on a change of practice of referring clinicians which did not materialize. ConclusionThe surgical treatment of drug-resistant temporal lobe epilepsy has been validated using RCT methods. Ways to promote participation in surgical trials should be further investigated.

Combined [18F]FDG-PET with MRI structural patterns in predicting post-surgical seizure outcomes in temporal lobe epilepsy patients.

To integrate the glucose metabolism measured using [18F]FDG PET/CT and anatomical features measured using MRI to forecast the post-surgical seizure outcomes of intractable temporal lobe epilepsy. This retrospective study enrolled 63 patients with drug-resistant temporal lobe epilepsy. Z-transform of the patients' PET images based on comparison with a database of healthy controls, cortical thickness, and quantitative anisotropy (QA) of the diffusion spectrum imaging concordant/non-concordant with cortical resection was adopted to quantify their predictive values for the post-surgical seizure outcomes. The PET hypometabolism region was concordant with the surgical field in 47 of the 63 patients. Forty-two patients were seizure-free post-surgery. The sensitivity and specificity of PET in predicting seizure freedom were 89.4% and 68.8%, respectively. Complete resection of foci with overlapped PET, cortical thickness, and QA abnormalities resulted in Engel I in 27 patients, which was a good predictor of seizure freedom with an odds ratio (OR) of 19.57 (95% CI 2.38-161.25, p = 0.006). Hypometabolism involved in multiple lobes (OR = 7.18, 95% CI 1.02-50.75, p = 0.048) and foci of hypometabolism with QA/cortical thickness abnormalities outside surgical field (OR = 14.72, 95% CI 2.13-101.56, p = 0.006) were two major predictors of Engel III/IV outcomes. ORs of QA to predict Engel I and seizure recurrence were 14.64 (95% CI 2.90-73.80, p = 0.001) and 12.01 (95% CI 2.91-49.65, p = 0.001), respectively. Combined PET and structural pattern is helpful to predict the post-surgical seizure outcomes and worse outcomes of Engel III/IV. This might decrease unnecessary surgical injuries to patients who are potentially not amenable to surgery. • A combined metabolic and structural pattern is helpful to predict the post-surgical seizure outcomes. • Favorable post-surgical seizure outcome was most likely reached in patients whose hypometabolism overlapped with the structural changes. • Hypometabolism in multiple lobes and QA or cortical thickness abnormalities outside the surgical field were predictors of worse seizure outcomes of Engel III/IV.

Changes of oxygen saturation in patients with pure temporal lobe epilepsy

PurposeIctal hypoxemia is accepted as one of the mechanisms underlying sudden unexpected death in epilepsy (SUDEP). Although ictal hypoxemia is more common in generalized seizures, it also occurs in focal seizures with or without generalization. In this study, we aimed to show the relationship between clinical and electroencephalographic findings of seizures in patients with temporal lobe epilepsy (TLE) with periictal oxygen saturation. MethodsThe data of 55 adult patients who were hospitalized in the Video EEG Monitoring Unit (VEMU) and operated on for drug-resistant TLE between January 2017 and December 2020 were examined. Forty-five seizures from 21 patients with ictal peripheral arterial saturation information and that were seizure-free for at least a year during the follow-up were included in the study. ResultsThe median patient age was 28 (IQR 25–39.5) years (women: 9, men: 12). Age at epilepsy onset was negatively correlated with saturation at seizure onset. Moreover, the age at VEMU admission was also negatively correlated with saturation at seizure onset and the lowest levels of saturation. The saturation at the end of the seizures and the lowest saturation measured in the periictal period with generalization of EEG were significantly lower than those without generalization.The onset of ictal EEG with the rhythmic theta pattern was significantly associated with the lowest level of saturation (<90%), postictal generalized electroencephalographic suppression (PGES), and the presence of generalization. ConclusionAccording to the study, rhythmic ictal theta activity, older age, nocturnal seizure, and generalization in ictal EEG might increase the potential risk of SUDEP. Further studies including a greater number of subjects and different epilepsy syndromes may provide more comprehensive information about potential biomarkers for SUDEP.

Validity of intraoperative ECoG in the parahippocampal gyrus as an indicator of hippocampal epileptogenicity

PurposeIntraoperative electrocorticography (ECoG) in the parahippocampal gyrus is sometimes used as a substitute for intraoperative ECoG in the hippocampus. This study aimed to elucidate the validity of parahippocampal ECoG as an indicator of hippocampal epileptogenicity. MethodsWe retrospectively identified 10 patients with drug-resistant unilateral mesial temporal lobe epilepsy who achieved Engel class I or II after anteromedial temporal lobectomy. Intraoperative ECoG was recorded in the parahippocampal gyrus and hippocampal alveus at sevoflurane concentrations of 1.5–3.0%. We sought to identify the sevoflurane proconvulsant effects on spikes and high-frequency oscillations (HFOs) on spikes in the epileptogenic area. The number of spikes and number of HFOs superimposed on spikes were counted in ECoG recordings of the parahippocampal gyrus, hippocampal alveus, and lateral temporal lobe, and analyzed using two-way repeated-measures analysis of variance. ResultsThe number of spikes and number of HFOs superimposed on spikes significantly increased as the sevoflurane concentration increased in both the hippocampal alveus and parahippocampal gyrus (spike, p < 0.001; ripple, p < 0.001; Fast ripple (FR), p < 0.001), and the pattern of increase was similar in these two areas.The number of spikes and number of HFOs on spikes were statistically higher in the hippocampal alveus than in the parahippocampal gyrus (spike, p = 0.004; ripple, p = 0.005; FR, p = 0.001). There were almost no spikes or HFOs on spikes in the lateral temporal lobe at sevoflurane concentrations in the range of 1.5–2.5%. ConclusionsIntraoperative ECoG in the parahippocampal gyrus can serve as an indicator of hippocampal epileptogenicity.

Epilepsy surgery for drug-resistant temporal lobe epilepsy in over-50 year-olds: Seizure outcome, surgical complications and neuropsychological outcome

ObjectiveSurgery is an effective treatment for drug-resistant temporal-lobe epilepsy (TLE), but is still underutilized for older patients because of a perceived higher rate of perioperative complications, cognitive decline and worse seizure outcome. MethodsWe retrospectively screened all patients operated on in our institution for drug-resistant TLE between 2007 and 2019. Data of patients aged ≥50 years versus <50 years at surgery were compared. The primary endpoint was freedom from disabling seizure (Engel I) at 2 years postoperatively. ResultsIn patients aged ≥50 years (n=19), mean age at surgery was 54.9 years and mean disease duration was 36.6 years. At 2 years postoperatively, rates of Engel I seizure outcome were not significantly different between the two groups (73.9% in the <50 years group versus 94.4% in the ≥50 years group). Although surgical complications were significantly (47.4%) in the older patients, neurological deficit was permanent in only 5.3% of cases. At 1 year postoperatively, neuropsychological outcome did not significantly differ between the two groups. ConclusionsPatients aged ≥50 years had an excellent seizure outcome at 2 years postoperatively. Early postoperative complications were more frequent in patients aged ≥50 years but were mostly transient. Cognitive outcome was similar to that in younger patients. These findings strongly suggest that age ≥50 years should not be an exclusion criterion for resective epilepsy surgery in patients with drug-resistant TLE.

Limited resection preserved verbal memory outcome in drug-resistant dominant temporal lobe epilepsy due to temporal encephaloceles (S24.002)

Limited resection preserved verbal memory outcome in drug-resistant dominant temporal lobe epilepsy due to temporal encephaloceles (S24.002)